Electrically-heated cup and method of producing same



Nov. 15, 1927. 1,649,067

J. H. KARLSON ELECTRICALLY HEATED CUP AND METHOD OF PRODUCING Filed Jul15, 1925 2 Sheets-Sheet 1 Nov. 15, 1927. I 1,649,067

J, H. KARLSON ELECTRICALLY HEATED CUP AND METHOD OF PRODUCING SAME FiledJuly 13, 1925 2 sheets-Sheet 2 Patented Nov. 15, 1927.

UNITED STATES 1,649,067 PATENT OFFICE.-

JULIUS H. KARLSON, OF CHICAGO, ILLINOIS.

ELECTRICAlDLY-HEATED CUP AND METHOD OF PRODUCING SAME.

Application filed July 13, 1925. Serial No. 43,166.

1 element, existing as a helix around the container, will not only haveits convolutions thoroughly insulated from the container and from oneanother, but be insulated from fpossible contact with a body exterior tothe winding and from outward dissipation of heat by radiation orconvection. Accordingly, one feature of the invention consists inapplying to the vessel to be heated, a surface of electricallynon-conducting material such, for instance, as sheet mica, winding ahelix of electric resistance wire upon said. surface, with theconvolutions spaced apart, winding a cord of insulating material, forinstance, asbestos fiber, in the spiral path defined by the spacedconvolutions of the resistance wire, and then winding a cord ofinsulating material in the grooves defined by the insulating cord firstapplied, and therefore in position to overlie the convolutions of theresistance element and complete the housing of the latter, and theirheat dispelling insulation on all sides excepting that provided by thewall to be heated.

Another object of the invention is to provide an improved outlet for theends of the resistance element in a construction of the kind described,and to equip the same with terminals adapted to enter an outletreceptacle and effect electrical connection of the cup with a source ofelectricity by the act of placing the heating container in position. Tothis end, another feature of the inven tion consists in enclosing theheating container, after equipping it with the housed re- 5 sistanceelement, as above described, in an outer shell, uniting the ends of theresistance element to binding posts extending through the bottom of saidshell and into an insulation block beneath the bottom, and introducingthe circuit closing terminals through the insulation block and into saidbinding posts; the binding posts being insulated from the bottom of theshell by means of an insulating plate underlying the heads of thebinding posts, and non-conducting bushings surrounding the portions ofthe binding posts which pass through said bottom; the binding postsbeing secured in such position by means of nuts screwed upon the ends ofthe binding posts and seated against the insulating block, and theinserted ter- 'minals passing radially through the nuts and into thebinding posts, and thereby permanently locking the nuts againstunscrewing. Preferably, the outer'shell has its side walls extended adistance beneath its bottom suflici-ent to support its bottom, with theinsulating block and contained equipment above the surface upon whichthe shell stands, and the insulating block has a removable cover whichcompletes the enclosure of the securing nuts and the ends of the bindingpost upon which they are mounted.

In the accompanying drawings,-

Figure 1 is a vertical axial section of an electrically heated cupprepared in accordance with the method and embodying the severalstructural features constituting the subject-matter of the presentinvention.

Figure 2 is a section through a portion of said cup, the plane ofsection being indicated by the line 2 x of Figure 1.

Figure 3 is a section on the line 8"- x of Figure 1, looking upward.

Figure 4 is a schematic view illustrating the method of applying to theexterior of the inner wall of the cup the electric resistance elementand the cord for insulating the same.

Figure 5 is a view illustrative of the method of applying solder to thejoint between the inner and outer walls of the cup.

Referring to Figures 1, 2, and 3, 1 represents the inner wall of a cupor container for fluid to be heated, 2 an electrical resistance elementcoiled about said wall for the purpose of heating the same, and 3 anouter wall concentric with the wall 1',providing means for supportingthe latter and developing therewith a space or chamber in which tolocate the electric heating equipment. The resistance element 2 is inthe form of a wire wound upon the exterior surface of the inner wall 1,after said wall has been faced With sheet mica or other substanceefficient as an electrical insulator but relatively low in theinsulation of heat, and the convolutions of the resistance element arespaced apart sufficient to have wound between them convolutions 4 ofasbestos cord or other substance which is highly resistant to heat inaddition to being an electricalnon-conductor; the effect of thus windingthe insulating cord between the convolutions of the resistance elementbeing to define a helical channel for the latter. The ends 2 2 of theresistance element thus wound upon the wall 1 are led in any suitableway, for instance, as indicated in the drawing, to a pair of bindingposts 5 beneath the bottom of the container 1, and there firmly fixed ina manner to adapt the binding post to serve as means for introducing theresistance element into an electric circuit, as hereinafter described.Having developed the spiral channel for the resistance element 2, saidchannel is closed on the outer side by a sub stance that is anon-conductor of both heat and electricity, for instance, a secondhelical winding 6 of asbestos cord, confined in position by theconvolutions of the cord first wound on, said closing cord resting uponthe cord first wound in a manner to close the grooves against escape ofheat from the resistance element either by radiation or convection.

In winding the resistance element and the insulating material upon thereceptacle 1, a procedure may be followed such as suggested in Figure 1,wherein 7 represents a revolving head designed to receive the upwardlyflaring portion 8 of the receptacle and hold the latter with itscylindrical portion 1 in position to receive the wire 2 from a reel ofwire 2*, and an asbestos cord 4 from a reel 4. The outer winding ofinsulating cord will be applied in the same manner.

Binding posts 5 are mounted in the bottom 9 of the outer shell 3 of thecontainer, being arranged with their heads resting upon a sheet 10 ofmica, with their shanks protected from contact with the bottom 9 throughmeans of fiber or other'insulating sleeves 11, while their lower ends 12are threaded into spanner nuts 13 housed in an insulating block 14- andseated against shoulders 15 in said block. A cover plate 16 ofinsulating material, secured by screws 17 to the block 14 and alsocemented to said block, completes a hermetic housing for allelectrically conductive parts in contact with binding posts 5, andrenders the electrical connection thoroughly waterproof and the cupimmune from impingement by water used in washing it.

In order to complete a circuit with the binding posts 5, terminals 18,fitted watertight through a wall of the block 14, extend radiallythrough the nuts 13 and into the lower ends of the binding posts in amanner to hold the terminals rigidly in a presentation which adapts themfor convenient introduction into the sockets of an outlet receptacle,and at the same time to prevent the nut 13 from unscrewing.

The outer shell 3 terminates in a bottom flange 19 which supports thecup with its bottom 9 sufficiently above the surface on which the cuprests to accommodate the block 14; and this supporting flange 19preferably terminates in an inwardly presented lip 20 which not onlyaffords a better foot for the cup but better adapts the cup to enterinto coaction with a sustaining projection when the cup is mounted inposition by the long known method of mounting a cup by moving it upwardto bring its upper marginal portion into engagement with a member thatsustains it laterally, and then swinging the cup inward until its bottomengages over a projection which affords vertical support.

In unitingthe shell 3 with the inner container 1, the latter ispreferably provided with a shoulder 21 adjacent the offset between thecylindrical portion 1 and flaring portion 8 of the cup, and againstwhich shoulder the shell 3 is made to abut; and a body of solder orother readily fusible metal 22 is placed in the angle between the innerand outer shells, as shown in Figure 5, so that when the cup is placedupon the rotary table 23 and rotated while played upon by torch 24, thesolder is melted and caused to flow by gravity in between the twosurfaces that are to be joined, which will include the concentric,conforming and approximately contacting faces of the inner cup flare andthe inner face of the outer shell, as well as the two edge faces whichabut at the shoulder 21.

I claim:

1. In the art of developing resistance elements upon electrically heatedcontainers, the steps which consist in winding the re sistance elementin spaced convolutions upon the wall of the container, winding a cord ofinsulating material in the spaces between said resistance element toprovide a helical channel for the resistance element, and winding a cordof material that is non-conductive of both heat and electricity in thesaid channel to complete the enclosure of the resistance element andprevent radiation or convection of heat outwardly therefrom.

2. In the art ofdeveloping electric heating means upon a container, thesteps which consist in providing upon the outer surface of the containera facing of material that is conductive of heat but non-conductive ofelectricity, winding upon the surface thus prepared a helix of electricresistance wire with convolutions spaced apart, winding in the spacesbetween the convolutions a cord of non-combustible material that isresistant to both heat and 'electricity, thereby developing walls of ahelical channel in which the resistance element lies, and then windingover said channel a cord of material resistant to heat and electricityand of a size that causes it to impinge against the sides of saidchannel formed by the cord first wound.

3. In an electrically heated vessel, 8. container, a facing of materialthat is conductive of heat but non-conductive of electricity, on theouter surface of said container, a helix of electric resistance wirewith convolutions spaced apart on said facing, means forming insulationencasing said wire, comprising a 4. In an electrically heated vessel, acontainer, a facing of material that is conductive of heat butnon-conductive of electricity, on the outer surface of said container,alternate convolutions of electric resistance Wire, and non-combustiblecord material th t is resistant to both heat and electricity, n saidfacing, other convolutions of non-combustible cord material positionedover the channels formed by said first named convolutions ofnon-combustible cord material, forming therewith a casing for said wireconvolutions.

5. In an electrically heated vessel, a container having a facing ofmaterial that is conductive of heat but non-conductive of electricity,on one surface thereof, convolutions of electric resistance wire. spacedon said facing, a casing over each convolution of wire comprising threecords of non-combustible material that is resistant to both heat andelectricity.

6. In an electrically heated vessel, an inner container, an electricalresistance element mounted on said inner container, an outer container,having a wall surrounding said inner container, and a bottom beneath andspaced from the same, and also having a depending skirt portion,providingwith said bottom a cavity, an electrically insulating block insaid cavity, binding posts extending from the space between said bottomand inner container, through said bottom and into the insulating block,said binding posts having the ends of said resistance element united tothem within said space, and terminals extending laterally through saiddepending skirt and into the side of said block and transversely intoportions of said binding posts located within the block, and means forhermetically sealing said terminals and binding posts.

Signed at Chicago, Illinois, this 8th day of July, 1925.

JULIUS H. KARLSON.

